The present embodiments relate generally to medical devices, and more particularly, to prostheses having branching portions.
The functional vessels of human and animal bodies, such as blood vessels and ducts, occasionally weaken or even rupture. For example, the aortic wall can weaken, resulting in an aneurysm. Upon further exposure to hemodynamic forces, such an aneurysm can rupture. One study found that in Western European and Australian men who are between 60 and 75 years of age, aortic aneurysms greater than 29 mm in diameter are found in 6.9% of the population, and those greater than 40 mm are present in 1.8% of the population.
One surgical intervention for weakened, aneurysmal, or ruptured vessels involves the use of an endoluminal prosthesis such as a stent-graft. Such a prosthesis may provide some or all of the functionality of the original, healthy vessel and/or preserve any remaining vascular integrity by replacing a length of the existing vessel wall that spans the site of vessel failure. It is preferable for the prosthesis to seal off the failed portion of the vessel. For weakened or aneurysmal vessels, even a small leak in the prosthesis may lead to the pressurization of or flow in the treated vessel which may aggravate the condition that the prosthesis was intended to treat.
In many cases, such a damaged or defective portion of the vasculature may include a branch vessel. For example, the celiac, superior mesenteric, left common carotid, and renal arteries are branch vessels of the aorta, and the internal iliac artery is a branch vessel of the common iliac artery. If the branch vessel is blocked by the prosthesis, the original blood circulation is impeded, and the patient can suffer. If, for example, the celiac artery is blocked by the prosthesis, the patient can experience abdominal pain, weight loss, nausea, bloating, and loose stools associated with mesenteric ischemia. The blockage of any branch vessel is usually associated with unpleasant or even life-threatening symptoms. Hence, it has been proposed to provide a prosthesis having a side branch which, when deployed, is positioned over the opening to a branch vessel. For example, the iliac branch of a bifurcated aortic prosthesis can be designed to extend into and/or provide flow to the corresponding internal iliac artery. Such a prosthesis is commonly referred to as an iliac branch device (IBD).
Various devices have incorporated a circumferential stent around the location of the coupling of the branch portion and trunk portion of a prosthesis. For example, a stent may encircle the trunk portion and then extend external to the branch portion, which is a general approach to keeping both the trunk and branch portions open at the same time.